/*
 * $Id: LabelValueBean.java 54929 2004-10-16 16:38:42Z germuska $ 
 *
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.struts.util;

import java.io.Serializable;
import java.util.Comparator;

/**
 * A simple JavaBean to represent label-value pairs. This is most commonly used
 * when constructing user interface elements which have a label to be displayed
 * to the user, and a corresponding value to be returned to the server. One
 * example is the <code>&lt;html:options&gt;</code> tag.
 * 
 * <p>
 * Note: this class has a natural ordering that is inconsistent with equals.
 * </p>
 * 
 * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
 */
public class LabelValueBean implements Comparable, Serializable {

    /**
     * Comparator that can be used for a case insensitive sort of 
     * <code>LabelValueBean</code> objects.
     */
    public static final Comparator CASE_INSENSITIVE_ORDER = new Comparator() {
    	public int compare(Object o1, Object o2) {
    		String label1 = ((LabelValueBean) o1).getLabel();
    		String label2 = ((LabelValueBean) o2).getLabel();
    		return label1.compareToIgnoreCase(label2);
    	}
    };


    // ----------------------------------------------------------- Constructors


    /**
     * Default constructor.
     */
    public LabelValueBean() {
        super();
    }

    /**
     * Construct an instance with the supplied property values.
     *
     * @param label The label to be displayed to the user.
     * @param value The value to be returned to the server.
     */
    public LabelValueBean(String label, String value) {
        this.label = label;
        this.value = value;
    }


    // ------------------------------------------------------------- Properties


    /**
     * The property which supplies the option label visible to the end user.
     */
    private String label = null;

    public String getLabel() {
        return this.label;
    }

    public void setLabel(String label) {
        this.label = label;
    }


    /**
     * The property which supplies the value returned to the server.
     */
    private String value = null;

    public String getValue() {
        return this.value;
    }

    public void setValue(String value) {
        this.value = value;
    }


    // --------------------------------------------------------- Public Methods

	/**
	 * Compare LabelValueBeans based on the label, because that's the human 
     * viewable part of the object.
	 * @see Comparable
	 */
	public int compareTo(Object o) {
		// Implicitly tests for the correct type, throwing 
        // ClassCastException as required by interface
		String otherLabel = ((LabelValueBean) o).getLabel();

		return this.getLabel().compareTo(otherLabel);
	}

    /**
     * Return a string representation of this object.
     */
    public String toString() {
        StringBuffer sb = new StringBuffer("LabelValueBean[");
        sb.append(this.label);
        sb.append(", ");
        sb.append(this.value);
        sb.append("]");
        return (sb.toString());
    }

    /**
     * LabelValueBeans are equal if their values are both null or equal.
     * @see java.lang.Object#equals(java.lang.Object)
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }

        if (!(obj instanceof LabelValueBean)) {
            return false;
        }

        LabelValueBean bean = (LabelValueBean) obj;
        int nil = (this.getValue() == null) ? 1 : 0;
        nil += (bean.getValue() == null) ? 1 : 0;

        if (nil == 2) {
            return true;
        } else if (nil == 1) {
            return false;
        } else {
            return this.getValue().equals(bean.getValue());
        }

    }

    /**
     * The hash code is based on the object's value.
     * @see java.lang.Object#hashCode()
     */
    public int hashCode() {
        return (this.getValue() == null) ? 17 : this.getValue().hashCode();
    }
}